Cathodic protection means



June 10, 1958 J. H. P. RANDALL 2,833,453

CATHODIC PROTECTION MEANS Filed Nov. 16, 1955 2 Sheets-Sheet 1 Fig.1.

June 10, 1958 1 J. H. P. RANDALL 2,333,453

CATHODIC PROTECTION MEANS Filed Nov. 16, 1955 2 Sheets-Sheet 2 the hatchway entrances.

United States Patent CATHODIC PROTECTION MEANS Jack H. P. Randall, London, England, assignor to F. A. Hughes & Co. Limited, London, England Application November 16, 1955, Serial No. 547,248

Claims priority, application Great Britain November 18, 1954 2 Claims. (Cl. 204-197) This invention relates to the protection of metal tanks in cargo ships against corrosion by the provision in electrical communication therewith of consumable anodes made of a metal or alloy anodic to the metal of the tank, or of anodes used with applied electric current.

The object of the present invention is to enable the anodes to be repeatedly removed, replaced or taken out of contact with the electrolyte or the contents of the tank being protected. It also envisages an easy arrangement for the replacement of consumed anodes.

The semi-permanent attachment of anodes to the tank surfaces is an expensive and time consuming matter and, in addition, considerable practical difliculty is occasioned in mounting and de-rnounting the anodes since weighty components have to be handled and access facilities, such as ladders and scaffolding, may be necessary. Since in some big tanks access to them is only available through a long tunnel-like hatchway extending to the upper deck of the vessel concerned, the use of normal crane facilities is hardly a practical possibility where anode assemblies have to be attached to the tank walls remote from Moreover, where anodes are attached to tank walls or to their strengthening structure, owing to their close proximity to the steel some method of insulating behind the anodes is essential in the interests of protective current spread.

According to the present invention the anodes are readily removable and replaceable and for this purpose they are carried on a supporting device which together with the anodes can be rolled or folded for storage. Visualizing such a structure adapted to the use of galvanic anodes with an operating position parallel to the tank sides, it may consist of two or more vertical ropes across which at right angles and at predetermined intervals are a number of metallic rods, the latter being suitably secured to the vertical ropes. Such rods may either be the cores on which magnesium alloy or other anodes were cast or, alternatively, suitably designed rods to which anodes could be attached. At the ends of these rods provision may be made to attach flexible electrical conductors which, in turn, may also be electrically connected to the tank structure. The vertical ropes may be manufactured from hemp, cotton, manila, synthetic materials such as nylon or the like, or flexible metal ropes may be used.

Instead of ropes rigid bars of metal or other material maybe used and such bar can be continuous or arranged to fold.

The invention will now be further described by way of example with reference to the accompanying diagrammatic drawings wherein:

Figure 1 is an elevational View of an arrangement made in accordance with the invention;

Figure Zis a side view thereof;

Figure 3 is a side view thereof when rolled;

Figure 4 is a side View thereof when folded;

Patented June 10, 1958 ICC Figure 8 is an elevational view of a further modification. i

The construction shown in Figures 1 to 6 comprises a pair of elements 10, 11 in the form of hemp ropes which are parallel to each other and have iron rods 12 connected to them at regular intervals. Each of the rods 12 is connected at opposite'ends to the elements 10, 11 respectively by means of a connector 15. Cast on each of the rods is a cylindrical block 16 of magnesium base alloy constituting an anode. The ropes 10, 11 and rods 12 form a supporting device for the anodes. Adjacent rods 12 are connected together by an electrical connector device 17 (Figure 5) and flexible metal conductor 18 and the uppermost rod 12 is connected by a similar device 17 and conductor 18 to the tank, e. g. to a bar 21.

The upper ends of the ropes 10, 11 are suspended by V loops 19, 20 to a bar 21 which may be specially provided for this purpose or may be part of the tank structure.

The lower end of each rope is attached to a beam 22 by means including right and left hand threaded nuts 23, 24 and a screwed bar 25 whereby the rope can be tensioned.

Figure 6 shows a construction in which the ropes are divided into short lengths each end of which is turned back on itself to form an eye 30 surrounding a metal eyepiece 31 that surrounds the bar 12. The two adjacent eyes are located axially between flanges 32, 33 on the rod 12. The ends of the rope lengths are clamped in their eye forming positions by clamps 34.

As shown in Figure 7 the ropes may be replaced by chains composed of links 26, provided at its ends with eyebolts 27 which surround the rods 12 to form a pivotal connection.

Figure 8 shows a modification in which more than three ropes 30 are provided, together with bars 12 whereby the supporting structure for the anodes is in the form of a mesh composed of bars at right angles to a series of ropes or like supporting elements which are parallel to each other.

When it is desired to remove such an anode assembly from the tank or to take it out of contact with the con tents, the afore-described structure permits this in different ways. Having detached the structure from the bottom of the tank, by a suitable arrangement of ropes or the like the structure can be gathered to the top of the tank in a similar manner to the action of a Venetian blind, or it can be rolled up. Thus as shown in Figure 3 it is rolled and in Figure 4 it is folded in layers. 7 method is to provide means to swing the bottom of the structure to a position at the top of the tank remote from its attachment so that the structure lies parallel to the roof or, as another alternative, the structure can be detached from the tank top and lowered to the bottom, permitting it to be rolled on the floor of the tank and taken out of the tank in this form via the hatchway. Such structures could be used vertically, as described, horizontally or at any intermediate angle.

Provision may be made through the top of the tank, such as specially designed access holes, to allow the various operations necessary for removal and re-fitment to be carried out by suitable means from the outside of the tank. Some similar arrangement may also be provided in the case where the structure is swung to the top of the tank.

Any desired number of such structures could be used in any one tank. The invention is applicable to tanker A cargo spaces and to any other container which would Figures 5 and 6 are views of details to be described;

Figure 7 is a side view of a modified construction; and

permit the use of such a structure.

I claim:

1. Means for the cathodic protection of ship tanks comprising a plurality of horizontally extending anode A further 3 blocks hung from the top of the tank like rungs of a ladder in vertically spaced position parallel to each other between two flexible electrically non-conducting ropes, and flexible metal conductors electrically connecting said anodes with each other and with the tank.

2. Means for the cathodic protection of ship tanks comprising a plurality of horizontally extending anode blocks hung from the top of the tank like rungs of a ladder in vertically spaced position parallel to each other between two flexible metallic ropes, said metallic ropes forming electrical conductors mechanically and electrically connecting said anodes with each other and with the tank.

References Cited in the file of this patent UNITED STATES PATENTS Kinnear Feb. 23, 1904 Mills Oct. 21, 1924 Tarr et al June 29, 1948 Kaufman May 16, 1950 Robinson et a1. Oct. 9, 1951 Harris et a1 Nov. 25, 1952 Waite et al. Apr. 24, 1956 FOREIGN PATENTS France 1904 France Jan. 30, 1952 

1. MEANS FOR THE CATHODIC PROTECTION OF SHIP TANKS COMPRISING A PLURALITY OF HORIZONTALLY EXTENDING ANODEBLOCKS HUNG FROM THE TOP OF THE TANK LIKE RUNGS OF A LADDER IN VERTICALLY SPACED POSITION PARALLEL TO EACH OTHER BETWEEN TWO FLEXIBLE ELECTRICALLY NON-CONDUCTING ROPES, AND FLEXIBLE METAL CONDUCTORS ELECTRICALLY CONNECTING SAID ANODES WITH EACH OTHER AND WITH THE TANK. 